1. Field of the Invention
The present invention relates generally to substrate and semiconductor wafer preparation systems and methods, and more particularly, the present invention relates to the cleaning of substrates and semiconductor wafers using an inventive brush box and employing space, process, and manufacturing efficient systems.
2. Description of the Related Art
In the fabrication of semiconductor devices, there is a need to perform wet cleaning of substrates at various stages of the fabrication process. Typically, integrated circuit devices are in the form of multi-level structures. At the substrate level, transistor devices having diffusion regions are formed over and into silicon substrates. In subsequent levels, interconnect metallization lines are patterned and electrically connected to the transistor devices to define the desired functional device. As is well known, patterned conductive layers are insulated from other conductive layers by dielectric materials, such as silicon dioxide. At each metallization level there is a need to planarize metal or associated dielectric material. Without planarization, fabrication of additional metallization layers becomes substantially more difficult due to the higher variations in the surface topography. In some applications, metallization line patterns are formed in the dielectric material, and then metal CMP operations are performed to remove excess metallization.
Following each CMP operation, a wet clean of the substrate is performed. The wet clean is designed to wash away any by-products of the fabrication process, remove contaminants, and to achieve and maintain the necessary degree of cleanliness essential to proceed to a subsequent fabrication operation. As transistor device structures become smaller and more complex, the precision required to achieve and maintain structure definition demands exacting standards of cleanliness be maintained in all process operations. If a wet clean is incomplete or ineffective, or if a post-wet clean drying is incomplete or ineffective, then unacceptable residue or contaminants are introduced into the processing environment.
Similarly, in the fabrication of hard disk drives, planarization and cleaning operations are needed to maintain a clean and smooth disk substrate. Residue or contaminants remaining on substrates in the fabrication of hard disks and other devices utilizing similar substrates is likewise unacceptable.
Substrate cleaning and scrubbing techniques, methods, and apparatus are plentiful and known in the art, and incorporate such operations as rinsing and scrubbing, immersion, and the application of thermal, mechanical, chemical, electrical, and/or sonic energy and the like to remove or displace water to dry the substrate. One known cleaning and scrubbing technique implements brush stations in which polyvinyl alcohol (PVA) brushes are used to scrub both sides of a substrate. In a typical brush station process, a substrate is rotated in a vertical orientation by substrate drive rollers, also called substrate edge wheels. As the substrate is rotated, a pair of cylindrical brushes or pads is brought into contact with the opposing surfaces of the wafer. The brushes or pads are mounted on counter-rotating mandrels disposed on opposite sides of the wafer being processed. The mandrels span the diameter of the substrate across the substrate center. The rotation of the mandrels rotates the cylindrical brushes or pads which are then applied against the opposing surfaces of the rotating substrate. During the scrubbing operation in some systems, nozzles direct sprays of liquid, e.g., an abrasive slurry, a chemical solution, or a rinse solution, on the opposing surfaces of the wafer. In some applications, liquid for polishing, scrubbing, or cleaning is supplied through the brush or pad, and some systems employ a combination of nozzles and fluid delivery through the brush or pad.
Substrate fabrication equipment is typically configured in integrated systems to maximize efficiency of processing by combining a plurality of fabrication processes to minimize substrate transfer and handling, to maximize the economical utilization of clean room floor space, and to maximize production throughput. Since a substrate wet cleaning is performed after many of the substrate fabrication steps, brush stations are often integrated into a plurality of fabrication and processing systems. By way of example, brush stations may be configured in pairs, side by side, with a pair of spin, rinse, and dry (SRD) tools configured vertically above the brush stations. Two brush stations are used, each with a pair of brushes, to enable the application of chemicals in one brush station and deionized (DI) water in the other. This dual brush station approach has been shown to improve the cleaning performance as well as increase throughput. In another typical configuration, each of the pair of brush stations performs the same scrubbing, cleaning, or other process operation, and the tandem implementation increases efficiency and throughput.
In typical prior art processing systems implementing one or more brush stations, the brush stations are specifically designed and configured for the particular system in which it is to be used, and often designed and configured for a specific location within an integrated system. Although many brush station parts, e.g., the brushes, are interchangeable between the various brush stations, each station is often unique to a particular implementation, and a specific location within the system, and typically requires manufacture of individual and specific components or parts for specific locations or implementations.
In view of the foregoing, there is a need for substrate brush station preparation systems and methods that provide modular and interchangeable brush stations with ease of access for service, ease of configuration for a plurality of system implementations, case of configuration for a plurality of substrates and substrate sizes, and that maximize the cleaning and processing of wafers and other substrates in order to meet and exceed the ever more stringent cleanliness requirements for fabrication processes.